Which of the following is not a type of brake fluid?

The classification of brake fluids primarily follows the Brake Fluid Standards of the Society of Automotive Engineers (SAE). DOT 3, DOT 4, and DOT 5 are recognized types of brake fluids that have specific boiling points and chemical compositions.

DOT 3 and DOT 4 are both glycol-based fluids, though DOT 4 has a higher boiling point than DOT 3, making it suitable for vehicles that may experience more extreme braking conditions. DOT 5, on the other hand, is a silicone-based fluid, which offers different properties such as being non-hygroscopic, meaning it does not absorb moisture from the air.

DOT 2, however, is not officially recognized in contemporary regulations for brake fluids. It is considered an outdated designation that was used in the past but is not commonly found or used in modern vehicles. This makes it the non-existent type of brake fluid within the current classifications. Therefore, identifying DOT 2 as not a type of brake fluid aligns with the understanding of current automotive standards and practices.